The Psalterium Sinaiticum is a 209-folio Glagolitic Old Church Slavonic

Old Church Slavonic

Old Church Slavonic or Old Church Slavic was the first literary Slavic language, first developed by the 9th century Byzantine Greek missionaries Saints Cyril and Methodius who were credited with standardizing the language and using it for translating the Bible and other Ancient Greek...

 canon manuscript

Manuscript

A manuscript or handwrite is written information that has been manually created by someone or some people, such as a hand-written letter, as opposed to being printed or reproduced some other way...

, the earliest Slavic psalter

Psalter

A psalter is a volume containing the Book of Psalms, often with other devotional material bound in as well, such as a liturgical calendar and litany of the Saints. Until the later medieval emergence of the book of hours, psalters were the books most widely owned by wealthy lay persons and were...

, dated to the 11th century. The manuscript was found in the monastery of Saint Catherine, Mount Sinai

Saint Catherine's Monastery, Mount Sinai

Saint Catherine's Monastery lies on the Sinai Peninsula, at the mouth of a gorge at the foot of Mount Sinai in the city of Saint Catherine in Egypt's South Sinai Governorate. The monastery is Orthodox and is a UNESCO World Heritage Site...

, after which it was named and where it remains to this day.

The major part of the psalter (177 folios) was discovered in 1850 by the Russian archimandrite

Archimandrite

The title Archimandrite , primarily used in the Eastern Orthodox and the Eastern Catholic churches, originally referred to a superior abbot whom a bishop appointed to supervise...

 Porfirij Uspensky, and additional 32 folios turned up in 1968.

It was published by L. Geitler (Psalterium. Glagolski spomenik manastria Siani brda; Zagreb 1883), S.N. Severjanov (Sinajskaja psaltyr'. Glagoličeskij pamjatnik XI veka. Prigotovil k pečati Sergej Sever'janov; Saint Petersburg 1922, transcribed to Cyrillic; reprinted in Graz in 1954) and by Moshe Altbauer in 1971, in a facsimile

Facsimile

A facsimile is a copy or reproduction of an old book, manuscript, map, art print, or other item of historical value that is as true to the original source as possible. It differs from other forms of reproduction by attempting to replicate the source as accurately as possible in terms of scale,...

 reproduction (Sinajski psaltir, glagolski rakopis od XI. vek od manastirot Sv. Katerina na Sinaj, MANU, Skopje 1971). The manuscript is also extensively discussed with facsimile reproductions in Ioannis C. Tarnanidis: The Slavonic Manuscripts Discovered in 1975 at. St. Catherine's Monastery on Mount Siani (Thessaloniki 1988).

Paleographic and linguistic analysis shows that the writing of some letters is very inconsistent. Especially inconsistent is the writing of yer

Yer

The letter yer of the Cyrillic alphabet, also spelled jer or er, is known as the hard sign in the modern Russian and Rusyn alphabets and as er golyam in the Bulgarian alphabet...

s and nasal vowels, and very obvious is the tendency of the vocalization of jers and the omission of epenthetic l.